1. Field of the Invention
The present invention relates to a method and a system for manufacturing a magnetic recording medium such as a magnetic tape.
2. Description of the Prior Art
A magnetic recording medium is generally manufactured in the form of a magnetic tape by applying magnetic paint containing a magnetic material onto a substrate serving as a long nonmagnetic support, applying a necessary treatment such as a magnetic-field orientation treatment to the substrate, drying the paint, and then smoothing the surface of the substrate.
The magnetic-paint applying method includes the gravure method, reverse method, and die method. In the case of the gravure coating method among the above methods, magnetic paint is applied to a gravure roller 7 to which a knurling treatment 8 (constant-directional longitudinal groove is formed) is applied as shown in FIG. 3.
The magnetic paint on the gravure roller 7 is transferred by setting a nonmagnetic support of a magnetic recording medium, that is, a base film (substrate) 5 between the gravure roller 7 and a back roller 9 and pressure-welding them.
Then, the surface of the substrate 5 to which the magnetic paint is applied is smoothed by a smoother 16, then made to pass through the cutting step, and a magnetic tape is obtained.
In this case, if the magnetic paint is applied up to ends of the substrate 5, various problems occur in that the magnetic paint attached to the gravure roller 7 is dried, removed, and scattered. Therefore, the magnetic paint is not applied to portions up to approx. 10 mm from ends.
Moreover, if the gravure roller 7 with the magnetic paint attached is rotated at a high speed, the thickness of the magnetic paint increases at only both ends of the gravure roller 7 due to knurling of the gravure roller 7 and the thickly attached paint is scattered due to rotation of the gravure roller 7.
Therefore, a resin plate referred to as a doctor blade 4 is provided for each end of the gravure roller 7 and pressed against the gravure roller 7 at a constant pressure to scrape off the magnetic paint.
An air tube 15 is set to a doctor blade 4 to take in scraped paint tailings by air and thereby prevent a recording or reproducing error from occurring due to attachment of paint tailings on a magnetic tape.
If the doctor blade 4 is used for a long time in the above manner, the air tube 15 is immediately clogged, paint tailings are not taken in, paint tailings scatter due to vibration of rotation, pressed marks of paint tailings are formed on a magnetic tape or paint tailings are attached to the tape. Therefore, it is necessary to replace the air tube 15 whenever the problem occurs.